Prehospital pulse oximetry: useful or misused?

This study evaluated the ability of emergency medical technicians (EMT-As) and emergency medical technicians-paramedics (EMT-Ps) to use pulse oximetry measurements in determining patient oxygen requirements.

Prospective case series.

Cleveland emergency medical services (EMS) system.

Five hundred thirty-two consecutive patients transported to Cleveland area hospitals by the Cleveland EMS system; no exclusions.

EMT-Ps and EMT-As predicted patients' supplemental oxygen requirements based on clinical assessment. Pulse oximetry was performed while patients were breathing room air (RA SpO2). Treatment intervention, including oxygen supplementation and medication given, oxygen saturation after intervention, and oxygen saturation on arrival at the hospital, was also recorded. Therapy guided by the patient's initial RA SpO2 was reviewed to determine the appropriateness of oxygen therapy.

Data were analyzed using the chi 2 test and correlation analysis. Eleven percent (59) of patients transported by Cleveland EMS had an initial RA SpO2 of less than 91%. Advanced life support units increased oxygen supplementation on all desaturated patients, whereas basic life support units failed to make appropriate increases in FIO2 in 20% (two) of desaturated patients (P less than .0001). Sixty percent (164) of patients transported by EMT-Ps and 62% (162) of patients transported by EMT-As had an initial RA SpO2 of 97% or greater. EMT-Ps gave supplemental oxygen therapy to all but 7% (11) of these already well-saturated patients, and EMT-As gave supplemental oxygen to all but 6% (nine) of these patients. EMT-Ps administered a higher FIO2 than they had predicted clinically necessary to 2% (four) of patients with an initial RA SpO2 of 97% of greater, whereas EMT-As gave a higher FIO2 than initially predicted to 16% (25) of such patients (P less than .0001).

EMT-Ps were more likely to appropriately base oxygen therapy on oximetry measurements than were EMT-As. Both groups failed to decrease supplemental oxygen in patients with high explicit protocols for EMS systems contemplating the use of oximetry to guide oxygen therapy. Our results further suggest that pulse oximetry could be used to avoid unnecessary oxygen therapy on a significant number of patients transported by EMS systems because they are already well saturated on room air.